Various ester compounds have been used as plasticizers in polymeric compositions. These plasticizers include, for example, alkyl phthalates and adipate esters. In recent years, various plasticizers based on renewable materials have been introduced. These include those based on citric acid (e.g., from Vertellus), succinic acid (e.g., from BioAmber and Myriant), vegetable oil (e.g., from Danisco and Dow Chemical Co.), isosorbide (e.g., from Roquette), and levulinic acid (e.g., from Segetis). Most of these renewable materials are compatible with polyvinyl chloride but may not be suitable for use with more hydrophilic polymers.